The present invention relates to a method for forming an organic semiconductor film used in thin film transistors or the like using organic semiconductor materials.
Organic semiconductor elements having organic semiconductor films (organic semiconductor layers) including organic semiconductor materials are used in devices using logical circuits such as thin film transistors (TFTs), RF tags (RFIDs), or memory used in liquid crystal displays or organic EL displays due to their ability to reduce weight, lower cost, and enhance flexibility.
In the production of an organic semiconductor element, one known method of forming an organic semiconductor film is a wet process of forming an organic semiconductor film by applying a coating prepared by dissolving an organic semiconductor material in a solvent to a substrate and then drying the solution.
This method for forming a wet organic semiconductor film has various advantages in that an organic semiconductor film can be formed inexpensively and that an organic semiconductor film can be formed in accordance with a large area.
Incidentally, in order to obtain an organic semiconductor film with high mobility, it is important to enhance the crystallinity of the organic semiconductor film. Therefore, various methods of improving the crystallinity of an organic semiconductor film have also been proposed in such a method of forming the wet organic semiconductor film.
For example, WO 2007/142238 describes a method of forming organic semiconductor crystals by forming a frame so as to enclose the formation position of an organic semiconductor film on a substrate, filling the frame with a solution in which an organic semiconductor material is dissolved, and then drying the solution.
In addition, WO 2011/040155 describes a method of forming a crystalline organic semiconductor film by using a contact member having a contact surface to which a solution in which an organic semiconductor material is dissolved is adhered, arranging the contact member so that the contact surface has a specific relationship with respect to the surface of the substrate, and then holding and drying the solution on the contact surface of the contact member.
Specifically, a method of forming a crystalline organic semiconductor film by using a contact member having a contact surface erected vertically on a substrate, filling a corner part formed by the contact surface and the substrate with a solution, and then drying the solution is described. In addition, a method of forming a crystalline organic semiconductor film by using a contact member having a contact surface which slopes with respect to a substrate, arranging the contact surface and the substrate so as to be separated by a prescribed spacing, filling the space between the contact surface and the substrate with a solution in contact with both the contact surface and the substrate, and then drying the solution is described as another method.